Envantage Method Translator GCC2011

Fast Temperature Programmed Gas Chromatography

of n-Paraffins through C14

GULF COAST CONFERENCEOct 11, 2011

Paper Presentation - 30 minutes – 2:30 PM: Abstract # 053

Walter Spieksma David Balazs Jay Grills

www.envantage.com

[email protected]

Envantage Method Translator

• Temperature programmed method translation• Nitrogen, Helium and Hydrogen• Dimethylsilicone or customized• Predict performance by EMT first principles• Real time demo after these slides

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Walter began his talk by summarizing the main

features of the Envantage Method Translator



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The Envantage Method Translator

(EMT) is an interactive tool that can be

used to help speed up gasoline range

GC methods by graphically displaying

quality measurements in a comparative

way



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This eliminates the expensive and time

consuming process of trial and error

that must be used with other Method

Translators



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The EMT does this by utilizing the Golay

equation and applying Boltzmann’s gas

diffusion laws as modified by Enskog-

Chapman while at the same time

considering the pneumatics of Hagen-

Poiseuille as well as….



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….well…you get the idea. There are a lot

of chemical and gas properties behind this.



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After describing the features of the

Envantage Method Translator Walter

demonstrated a few real-world examples

of analytical problems that can be

addressed using the EMT



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In this excerpt of his talk just a few of the

EMT tools will be described and one

quick example will be given

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Agilent Method Translator

This popular tool

has a nice interface

to enter the original

Method parameters

11


And new column

parameters

12


A new pressure and

temperature program

is translated and

displayed

13


But how do you

know how well this

translated Method

will perform?


Agilent Technologies, Inc., Application Note 228-294. 14

As an example of how the

translator works the

documentation shows

comparison chromatograms

with clear differences

between them



The column type and

dimensions are quite

different from each other so

the example is confusing



Toggle back and forth

between this slide and the

next to see the differences

in the chromatogram



18


This tool is easy to use

and you will get a

chromatogram – but

what if you need the

new chromatogram to

look like the one in

your original Method?


19

The next 4 slides will show the Envantage Method

Translator interface and two “before and after”

chromatograms of an ASTM method that was translated

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21

Note:

•the quick assessment of Speed, Sensitivity, and Resolution

•the change in run time

•the similarity of the chromatograms

•comparable chromatographing power

TPGC D 6730

22

Take a look at the front end of a

chromatogram obtained by

analyzing a sample with a standard

ASTM Method, and the same

sample chromatogram after the

method has been optimized for

speed with the EMT (toggle this

slide with the next)

Fast TPGC

23

Going from 60 to 11 minutes is

considered by most to be a

pretty nice speed-up!

24

So let’s take a closer

look at the EMT

interface

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First the table

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The table has familiar

functionality:

a place to enter original

Method settings and

new Method settings

27

Any two

combinations of

Column Length,

Hold-up time, or

Head Pressure can

be “locked” so that

the third can be

calculated

28

Footnotes at the

bottom provide clues

to things you should

be aware of – like

high pressures the

instrument may not

be capable of

29

There are also

options to display

Column IDs in

mm, time in

seconds, and

pressures in

kPa, bar, or atm

30

Constant pressure,

velocity, or temperature

can be selected at the

bottom of the table

31

Next, let’s look at the “Trilemma” display

32

The “Trilemma” displays

the interdependence of

Speed, Sensitivity, and

Resolution when

translating a Gas

Chromatographic method

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“Speed” (speed gain)

is the ratio of holdup

time of the original

method and the new

method. “Resolution”

is the peak width ratio.

“Sensitivity” is the

peak height ratio.

34

Speed gain can be

changed by the user

with the up and

down buttons; the

resolution and

sensitivity

consequences are

displayed.

35

Pressing the

“Optima” button

results in a speed

gain proportional to

the ratio of the

optimum velocities

of both methods.

The “Integer” button

rounds off speed

gain so that

temperatures and

ramps are not

fractional

36

The change of

Speed, Sensitivity,

and Resolution will

be displayed as the

carrier flow is

changed following

the first principles of

the trilemma of

chromatography.

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The Trilemma display

will also change if

carrier flow changes

are made in the table

or by grabbing and

dragging the linear

velocity hash marks in

the “Plate Height” and

“Plate Number” tabs

38

Now let’s take a look

at some of these tabs;

in particular “Plate

Height”, “Plate

Number”, and

“Chromatogram”

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Let’s consider the “Plate

Height” tab

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When GC method

parameters are entered ,

EMT will calculate a HETP

curve of nC6 (similar to a

Van Deemter curve) and

locate the linear velocity.

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Note the absence of the

Trilemma display. It does not

appear until settings for a

new Method are entered into

the 2nd column of the table.

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As any good

chromatographer

knows - the lower

the HETP, the better

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As expected this

ASTM Method is

operating at optimum

linear velocity for

this column length,

ID, film thickness,

and carrier gas

44

EMT also calculates

and draws a “Plate

Number” chart. The

number changes

depending on the

linear velocity of the

carrier gas.

45

More is better and the

best can be achieved

at the optimum linear

velocity of the carrier

gas

46

EMT also calculates

the retention times of

n-alkanes through

nC14 and displays

them graphically in a

“chromatogram”

47

Click on the Trenn

Zahl toggle to display

a Trenn Zahl chart

under the

chromatogram

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What is a Trenn Zahl Chart?


It indicates how many peaks can elute between any two

n-alkanes


EMT calculates the peak widths of the theoretical n-

alkane peaks in the theoretical chromatogram and then

calculates how many peaks with a similar width can be

parked between any two n-alkane peaks


In this example almost 130

peaks can be parked

between n-C8 and n-C9


When optimizing Methods with complex chromatograms

this can be a useful tool to indicate the new Method has

the power to achieve the same separations as the original

method


So how well does the Envantage

Method Translator do all this

calculating?

EMT D 6733#1

54

This slide and the

next show

chromatograms

generated for ASTM

6733 #1 and #2 (one

cryogenic, one not)

EMT D 6733#2

55

D 6733 and EMT


xASTM D 6733#1 EMT*

(Calc-Exp)

/ExpASTM D 6733#2 EMT**

(Calc-Exp)

/Exp

tx [min.] tx [min.] % tx [min.] tx [min.] %

3 4.14 4.21 1.57 5.08 5.32 4.63

4 4.74 4.75 0.17 6.55 6.71 2.47

5 6.31 6.15 -2.50 11.12 11.02 -0.90

6 10.40 9.87 -5.13 23.39 23.07 -1.37

7 19.36 18.52 -4.34 40.58 40.42 -0.39

8 33.01 32.35 -2.00 57.70 57.80 0.17

9 48.85 48.71 -0.29 72.88 73.23 0.48

10 64.86 65.35 0.76 85.54 86.10 0.65

11 80.17 81.39 1.52 95.59 97.47 1.97

12 93.50 95.18 1.80 107.81 107.90 0.08

* Pgage = 192 kPa to get: (1) 18.5< t7 <20.3 (2) 32< t8 <34 (3) 92.8< t12 < 95.2 min.

**Pgage = 150 kPa to get: (1) 39.5< t7 <42.0 (2) 57< t8 <59 (3) 106.4< t12 <108.8 min.

This table shows how

well the EMT

calculated retention

times compare to the

ASTM published

values

0

20

40

60

80

100

120

140

160

180

0 20 40 60 80 100 120 140 160 180

En

va

nta

ge

Met

hod

Tra

nsl

ato

r [m

in]

ASTM [min]

TPGC retention time of n-Paraffins

EMT retention time

57

This chart plots how

well the EMT

calculated retention

times for several

samples correlate

with ASTM DHA

values

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To use the Envantage

Method Translator enter

original Method settings in

the left column, and new

Method settings in the

second column

59

When parameters for a new

Method are entered the

Trilemma display appears and

comparative charts and graphs

appear in the “Plate

Height”, “Plate Number”, and

“Chromatogram” tabs

60

Hash marks indicating the

linear velocity can be

“grabbed” with the mouse and

dragged. Head pressure will

change in the table and the

Trilemma display will show

the effects of this change

61

On the “Plate Number”

tab, hash marks indicating

linear velocity can also be

“grabbed” with the mouse and

dragged. In this example the

new Method has significantly

more plates and indicates the

column can be shortened to

achieve the same separation as

the original method

62

On the

“Chromatogram” tab

two chromatograms

appear

and, optionally, the

Trenn Zahl chart. If the

peaks line up and the

Trenn Zahl charts are

very similar then the

new Method may be a

good replacement for

the original Method.

ASTM with H2 carrier

• Helium prices rise for 10 years now

• Advice: Change to Hydrogen carrier; use the same head pressure you used with helium


And now for a real-world example…..


Chromatographers are often advised

to simply switch to Hydrogen carrier

gas and keep the same carrier gas

pressures used with helium. If you

ever tried this and met with poor

success – maybe this is why…..

Keep P


In this example the same column

dimensions are entered in both columns

of the table, making sure the column head

pressure is the same and only the carrier

gas is different

Keep P


Optima

With Hydrogen

the Method is

more sensitive

But there is less

separation

67

By inspecting

the linear

velocity on the

“Plate Number”

tab it is obvious

the column

flow is not

optimum

68

Click and drag

the hash line or

click on

“Optima” in the

Trilemma

display

Optimum Chromatograms


Note the new head

pressure; now the

sensitivity is the

just about the same

And, more importantly, the

separation is now the same.

Your new chromatogram

should match the old!

Optimum Chromatograms


Next, you might be

wondering if you

can shave more

time off this

Method by

adjusting the

column dimensions


The answer is…..probably.

But that’s another real-world example


More information about the

Envantage Method Translator will be

posted soon on our web site

Technology

Envantage Method Translator GCC2011